1. Field of the Invention
The present invention relates to a vitreous surgical apparatus for excising a part of a vitreous body in an eyeball, and aspirating and discharging the excised part out of the eyeball.
2. Description of Related Art
A vitreous body cutter used in vitreous surgery is operated to excise a part of a vitreous body in an eyeball of a patient""s eye by moving an inner tubular blade in an outer tubular fixed blade while drawing the part of the vitreous body by aspiration into an aspiration port provided in one end of the outer blade.
As such moving system of the inner blade, there has been known a guillotine type which moves an inner blade to reciprocate.
Moreover, as systems for driving an inner blade, there are an electrical system using a vitreous body cutter which mounts therein an electric motor or electromagnet, and a pneumatic system which drives an inner blade by repeating supply and exhaust of compressed air. This pneumatic system intermittently performs supply of compressed air from a compression pump into a cylinder constituted of a piston, a diaphragm, and others and exhaust of the air from the cylinder by control of opening and closing of a solenoid valve.
In vitreous surgeries, in particular, operations on the periphery of a retina, speedup of a cutting speed (a cutting rate) of the vitreous body cutter is requested. Accordingly, the number of reciprocating motions of the inner blade per unit of time needs to be increased.
To realize high-speed actuation of the pneumatically operated cutter, the solenoid valve which controls the supply of compressed air to the cutter needs a high responsivity for the supply of compressed air. Thus, the solenoid valve has to be designed to have an air flow passage of a larger effective diameter (caliber) and to open and close at a high speed. There is, however, no solenoid valve satisfying those requirements at present. Newly designing a solenoid valve with an air flow passage of a larger effective diameter will result in high cost. Hence it is difficult to materialize a high-speed cutter for vitreous surgery. Furthermore, a large-sized solenoid valve is usually slow in response speed. It is therefore difficult to produce a solenoid valve with high responsivity and capable of allowing a large amount of flow. Also, the large solenoid valve generally has a high noise problem.
If the vitreous body cutter is driven at a high speed, an open time of the aspiration port in the end of the cutter (outer blade) in each cycle is reduced than when actuated at a low speed. This would cause problems that aspiration efficiency lowers and cutting sharpness of the cutter with respect to a vitreous body deteriorates.
The present invention has been made in view of the above circumstances and has an object to overcome the above problems and to provide a vitreous surgical apparatus capable of actuating a cutter for vitreous surgery at a high speed by a simple structure, and enhancing cutting sharpness of the cutter actuated at a high speed.
Additional objects and advantages of the invention will be set forth in part in the description which follows and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the purpose of the invention, there is provided a vitreous surgical apparatus in which an inner tubular blade is moved in an axis direction with respect to an outer tubular blade by supply and exhaust of compressed air to excise a part of a vitreous body in an eyeball and aspirate and discharge the excised part out of the eyeball, the apparatus including: a plurality of solenoid valves each of which is opened and closed for performing the supply and exhaust of the compressed air; and control means which synchronously drives the solenoid valves to open and close in order to move the inner tubular blade at a desired cutting speed.
According to another aspect of the present invention, there is provided a vitreous surgical apparatus for excising a part of a vitreous body in an eyeball and aspirating and discharging the excised part out of the eyeball, the apparatus including: an outer tubular blade; an inner tubular blade movable in an axis direction with respect to the outer tubular blade; a piston to which the inner tubular blade is fixed; an air chamber in which the piston is movably disposed; a plurality of solenoid valves each having an output port being in communication with the air chamber, an aspiration port being in communication with a compressed air supply source, and an exhaust port through which the compressed air is exhausted, the solenoid valve being switched between communication between the output port and the aspiration port and communication between the output port and the exhaust port to alternately perform supply and exhaust of compressed air to and from the air chamber; and a control section which controls switching in each of the solenoid valves to move the inner tubular blade at a desired cutting speed.